Process for the production of an optical fiber bundle for heat resistance and vacuum resistance by bonding fiber ends with a bonding glass

Abstract

An optical fiber bundle for heat resistance and vacuum resistance which can be used even at a very high temperature or high vacuum is provided in economical manner. This is accomplished by a process for the production of an optical fiber bundle for heat resistance and vacuum resistance, which comprises making up optical fiber filaments each having a core part and a clad part into a bundle, closely fusion-bonding the end of the optical fiber bundle with a bonding glass and then subjecting the bonding glass to a crystallization treatment to increase the heat resistance.

What is claimed is: 
     
       1. A process for the production of an optical fiber bundle which comprises assembling optical fiber filaments, each having a core and clad part, into a bundle, contacting the optical fiber bundle at an end thereof with a bonding glass. having a softening point lower than that of said optical fiber filaments, tightly fusion bonding the end of said optical fiber bundle with said bonding glass, and then subjecting said bonding glass to a crystallization treatment, said bonding glass having a glass composition comprising 20 to 30 weight % of TeO 2 , 12 to 30 weight % of Bi 2  O 3 , 13 to 23 weight % of GeO 2 , 15 to 35 weight % of PbO, 0 to 12 weight % of La 2  O 3  and 0 to 20 weight % of Nb 2  O 5 , provided that the sum of the amounts of La 2  O 3  and Nb 2  O 5  is in the range of 5.0 to 20.0 weight % and optionally at least one oxide component selected from the group consisting of Li, Na, K, Cs, Mg, Ca, Zn, Sr, Ba, Ti, Y, Zr, Ga, In, Sn, Sb, Tl, As, Al, Gd, Yb, Ta, W and P oxides. 
     
     
       2. The process as claimed in claim 1, wherein the fusion-bonding with said bonding glass is carried out by heating the bonding glass to a temperature such that the bonding glass permeates throughout the end of the optical fiber binder and fusion-bonds the said end of the optical fiber bundle. 
     
     
       3. The process as claimed in claim 1, wherein the fusion-bonding is performed at a temperature of at most 700° C. and the glass crystallization is performed at a temperature of 500° to 700° C. 
     
     
       4. The process as in claim 1 wherein during the assembly the optical fiber bundle is held in a sleeve and during the contacting step the bonding glass is inserted into the sleeve so that it contacts the end of the optical fiber and wherein fusion-bonding of said optical fiber bundle is performed at temperatures such that the bonding glass fuses and permeates the end of said optical fiber bundle. 
     
     
       5. The process as in claim 4 wherein the sleeve is a metal sleeve.